We use administrative data from Washington State to perform a large-scale analysis of the impact of family formation on crime. Our estimates indicate that pregnancy triggers sharp declines in arrests rivaling any known intervention, supporting the view that childbirth is a “turning point” that reduces deviant behavior through social bonds. For mothers, criminal arrests drop precipitously in the first few months of pregnancy, stabilizing at half of pre-pregnancy levels three years after birth. Men show a sustained 20 percent decline in crime that begins at pregnancy, although arrests for domestic violence spike at birth. These effects are concentrated among first-time parents, suggesting that a permanent change in preferences—rather than transitory time and budget shocks—may be responsible. A separate design using parents of stillborn children to estimate counterfactual arrest rates reinforces the main findings. Marriage, in contrast, is not associated with any sudden changes and marks the completion of a gradual 50 percent decline in arrests for both men and women.